Apparatus for grinding and cooling solids



Nov. 13, 1962 o. G. LELLEP APPARATUS FOR GRINDING AND COOLING SOLIOs Filed NOV. 10, 1960 www 1.5....

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Filed Nov. 10, 1%0, Ser. No. 63,406 4 Claims. (Cl. 241-51) This invention relates to cooling granular material with gases. The invention is particularly useful for cooling the products of rotary kilns, and'in particular cement clinker.

These materials are often white hot when they are discharged from a rotary kiln. These materials must then be cooled suiliciently for safe and easy handling. Considerable economic advantage is gained by returning the heat of cooled material back into the rotary kiln. Machines usually used for cooling such materials comprise a grate upon which the material discharged from a rotary kiln is moved by a shaking mechanism or other means placed along the grates. These grates may have a length of from forty to one hundred feet. Large volumes of cooling air are blown upwardly through such a grate and the layer of material on it. This type of cooler is known as a crosscurrent cooler because the air passes through the material at a ninety degree angle to the moving layer of material. It is desirable that after this cooling air has passed upwardly through the hot material received from the furnace and the air has thereby itself become heated, the ynow quite hot air should pass into the furnace and contribute to the fuel economy of the system. Crosscurrent coolers however require volumes of cooling air to be passed through the grate that are greater than the volume of air required in the kiln. The excess air is disposed of by passing it up and out of a special stack provided for this purpose. Because only a portion of the air passing through a crosscurrent cooler finds it way into the kiln, the eiliciency of heat recovery from the hot material with such apparatus usually reaches not above sixty-ve percent.

The desire to reach heat recovery efliciencies above sixty-five percent resulted in the development of a type of cooler known as a countercurrcnt cooler. In this type of cooler, heated material is deposited in a vertical shaft and removed from the bottom of the shaft toprovide a continuously descending column of the material having substantially greater depth than material carried on Vthe grate of a vcrosscurrent cooler. Cooling air is supplied beneath the column of material and is blown upwardly through the descending column. The material to be `cooled moves downwardly and the cooling air upwardly through the shaft and hence the name countercurrent cooler. Since all of thecooling air passes through a column of hot material having muchl greater depth than the material deposited upon the vgrate of a crosscurrent cooler, the -cooling air passing through the hot material `in a countercurrent cooler is raised to a-much higher temperature than in a Vcrosscurrent cooler. As the cooling air passes upwardly through a countercurrent cooler, the

Ycoolest air comes in contact first with the coolest of the material in the column and as it travels upwardly through the column the air becomes warmer as it reaches levels of The cooling air finally passes from the top of the column and into the kiln. Since the last material that the cooling air cornes in contact with before entering the furnaceis the high temperature material just discharged from the furnace the-cooling air is steadily and continuously heated to a high temperature. Because the air passing through a countercurrent cooler is raised to a much higher temperature than the air passing through a crosscurrent cooler, each portion of such Irates arent rice y air performs a much greater amount of cooling and much` less volume of cooling air is required for the countercurrent type cooler than is required for a crosscurrent type cooler. The volumes of air required for the countercurrent type cooler are reduced sufficiently so that all of the cooling air passing through the cooler may-be passed on into the rotary kiln and no special stack is required to take away any excess air as is the case in a crosscurrent type cooler. As a result of the air passing `through a countercurrent cooler being raised to a very high temperature and that all of the air passing through this type of cooler enters the rotary kiln a much higher elliciency of heat recovery from material discharged from the kiln can be achieved with the countercurrent type cooler than has been achieved with the crosscurrent type cooler. It has been determined that the elliciency of heat recovery with a countercurrent cooler is in the neighborhood of ninety percent of the heat contained in the material when it is discharged from the rotary kiln.

In order to avoid a segregation of the material falling into the cooler according to grain size, it has been proposed to rotate a shaft cooler and direct the stream of hot material through hood structure arranged eccentrically to `the rotating shaft coole-r. To additionally improve distribution of the hot material in this type Aof cooler, it has been proposed to provide a swinging spout for discharging the hot material into the cooler. It was additionally proposed to `provide an inclined screen, of a type known as a grizzly, in the hood structure through which the material discharged from a kiln had to pass before falling int-o the shaft cooler. Such an inclined grizzly will screen out and discharge large lumps of material without permitting them to fall into the cooler. It is not possible, however, to use either a swinging distribution chute or an inclined grizzly with a cooler that is to be used for cooling material such as cement clinker which is discharged from a kiln at very high temperatures. Cement is discharged from a kiln to a cooler at temperatures in excess of 2500 degrees Fahrenheit and the metallic bars of a grizzly as well as any metallic distribution chute will burn out or corrode too rapidly to be practical. In addition to the desirability for eliminating a grizzly based upon the short life thereof itis also undesirable to have to discharge large lumps of material without having passed through the cooler because to do so results in a considerable loss of heat that is desired to be recovered for use in the kiln.

Because of the difficulties experienced heretofore with regard to distribution chutes and grizzlies for eliminating large lumps, cross current coolers are used in most cement operations despite the fact that a much lower percentage of heat is recovered from the cementvclinker when it is cooled.

It is therefore, a principal object of the present invention to provide an improved shaft type cooler that does not require either distribution apparatus or lump ejection apparatus.

Another object of the present invention is to provide a new and improved type shaft cooler in which large lumps of material will lbe reduced in size before they are discharged from the cooler.

Still another object of the present invention is to provide a new and improved shaft type cooler in which large Vlumps of material will be retained within the cooler long enough to be properly cooled and their heat recovered in addition to reducing the size of such lumps before they are discharged from the cooler.

According to a preferred embodiment of the present invention the appanatus includes a first bin and wind box assembly and a second assembly including a shaft the other. A hood is provided over the second assembly for delivering the hot material discharged from a kiln to the cooler near the periphery of the shaft. A blower is provided for blowing cooling gases upwardly through a column of material formed within the shaft. The discharge of material from the cooler is provided for by a mechanism including a pair of cooperating structures,

,one supported by the wind box and the bin assembly and another structure supported by the shaft assembly, The relative movement between the bin and wind box assembly and the shaft assembly of course imparts relative motion between the two structures of the discharge mechanism. The movable and nonmovable structures of the discharge device are spaced apart to deline a comminution space therebetween where lumps larger than predetermined maximum size are retained until they have both reduced in size and further cooled to obtain the maximum recovery of heat from them.

The invention will be better understood by reference to the following detailed description of an apparatus according to the present invention as particularly applied to cooling cement clinker or the like discharged from a rotary kiln and this description is to be considered together with the drawing in which:

FIG. l is a vertical cross section view of apparatus embodying the invention;

FIG. 2 is a vertical end View of the apparatus shown in FIG. l; and

FIG. 3 is a View taken along line III- HI in FIG. l looking in the direction indicated by the arrows.

Referring to the drawing, an embodiment of the present invention is shown in which a granular material such as cement clinker is received from a rotary kiln to be cooled. A portion of the discharge end of the kiln assembly is shown having a rotatable cylinder 1. The open end of cylinder 1 is enclosed by a tiring hood 2. A burner 3 proiects through a front wall portion of the firing hood and extends into the cylinder .1. Fuel is introduced into the cylinder 1 through the burner 3 and burned within the cylinder 1 to create the temperatures necessary to burn material such as the raw materials that produce cement clinker.

l As granular material is advanced through the cylinder 1 from the feed end (not shown) to the discharge end of the cylinder enclosed by the tiring hood, the material is progressively heated until at the point of discharge from cylinder 1 into tiring hood 2 it may be white hot. From the cylinder 1 the hot material is dropped through y a passage 4 dened by the firing hood 2, a collar 8 and is deposited in a cooler 9.

The cooler 9 includes a first assembly 11 and a second assembly 12 mounted over the first assembly 11. The lirst assembly 11 serves ias both a bin and a wind box in a manner that will appear as the description proceeds.

The second assembly 12 includes a shaft t13 carried by a circular track assembly 14. The shaft 13 is rotated on the circular track assembly 1'4 by a variable speed electric motor 15 `which is drivingly connected to shaft 13 b v means of la pinion gear 16 that is driven by the motor 15 and meshes with `a ring gear 17 secured around shaft 13 to rotate the shaft about its central axis. A controller 18 is provided to control the speed of the motor 15 which drives the shaft |13. A blower 22 is connected to a conduit 23 which is in turn connected to the iirst assembly 11 which thereby acts as a wind box for directing cooling air upwardly from the wind box or a iirst assembly 11 through the vshaft 13.

Discharge means 29 are provided for discharging material from the shaft 13 to the bin and windbox assembly 11. I'he discharge means 29 includes both the following described structure that is supported by the assembly 11 and structure that is supported by the assembly 12. An annular grate 30 having apertures 31 is supported by the bin and wind box assembly 11. A plurality of arms 40 are supported by the second assembly 12. The arms 40` are yadjacent the lower end of shaft 13 and connected to circumferentially spaced points on the shaft as may be seen in FIG. 3. Each of the larms 40 extend inwardly toward the central axis of the shaft 13. A first plurality of teeth 32 are provided on the annular grate A30 and these teeth project upwardly from the grate toward the arms 40. A second plurality of teeth 42 are provided on the lower surfaces of the arms 40 and project downwardly from the arms toward the grate 30 and teeth 32. It is desirable that a substantially larger number of teeth 32 be provided on the grate 30 than the number of teeth 42 on the arms 4Q. A cylindrical shell 43 is suspended from the inward ends of the arms 40 and the shell extends through the central opening of the annular grate 30 with its central axis in a vertical position. The arms 40 with their teeth 42 and the shell 43 therefore are carried by the assembly 12. Structure carried by the assembly 11 in addition to the grate 30, includes an eccentric crushing cone 34 having an axle 35 journaled in a spider 36 connected to the assembly 11. rthe cone 34 supported in this man ner projects upwardly into the shell 43. The structures carried by and turned by the assembly 12, namely 40, 42 and 43, 'are spaced lfrom the structures carried by the assembly 11, namely 30, 32 and 34, to define therebetween comminution space 50, 51 where lumps of material too large to pass through the apertures 3-1 wil-1 be retained until they are both reduced in size and further cooled.

The collar 8 and the hood structure 2 which cooperate to dene the discharge passage 4 from the kiln 1 to the cooler 9 provide for discharging the hot material near the periphery of the shaft 13. The cylinder 1, hood 2, passage 4, collar 8, and shaft 13 are all lined with a refractory material 5 which is usually tirebrick.

In the operation of the described apparatus, material such as cement clinker comprising both relatively small granules and occasionally large lumps are discharged from the kiln 1 through the passage 4, the collar 8 and are deposited on the grate 30 to build up a column of material within the shaft 13. On occasion this material deposited in the cooler 9 may even include pieces of frebrick that have broken away from the interior of the kiln 1. The speed of the operation of motor 15 may be controlled by the controller 18 to initially rotate the shaft 13 slowly enough to build up a column of material within the shaft of sufficient depth to cause the material to remain within the shaft long enough for the desired cooling to be achieved. Thereafter the speed of rotation of the shaft 13 can be controlled to maintain such a depth of material in the cooler. Since the passage 4 directs material from the kiln 1 into the cooler 9 near the periphery of the shell 13 a relatively uniform depth of material throughout the shaft is achieved. Particles small enough to pass through the apertures 31 in the annular grate 30 will trickle down through the column of material in shaft 13 and pass through these openings in the grate into the bin and wind box assembly 11. Material conveying means 19 may be provided beneath an opening 20 in the assembly 11 to carry the cooled material away from the cooler. The conveyor 19 may be operated slowly enough to insure maintaining a suicient depth of cooled material within the assembly 11 to prevent air coming in to the assembly 11 through conduit 23 making an exit through the opening 20 rather than going up through the shaft 13. Particles toolargel to pass through openings 31 in the grate 30 will, like the smaller particles, pass downwardly through the column of material in shaft 13. Such larger particles, however, will contain a considerable amount of heat and in addition to being too hot to handle it is desired that this heat be recovered in the cooling structure for use in thekiln 1. The described discharge means 29 provide that such larger particles are prevented from passing from the assembly 12 into the bin and wind box assembly 11. Such larger particles will be trapped and 5, retained within the comminution space 50, 51 until they are both reduced in size and further cooled. The reduction in size achieved withinV the comminution space 50 results from themoving arms40 pushing the larger particles around the top surface of the stationary grate where the teeth 32 will break up these larger particles. When the larger'particleshave'been reduced in size to pass Abetween the arms- 40 andthe grate 30 these particles will additionally -be reduced in size by the additional breaking action resulting from contact with the teeth 42 on the lower surfaces of the arms 40. Furthermore, clockwise rotation of the shaft 13 as indicated in FIG. 3 will result in these larger particles being moved relatively inwardly within the space between adjacent arms 40. The distance between arms 40 is less near the shell 43 than near shaft 13 as is shown in FIG. 3. Such larger particles will then either be reduced in size so that they can pass through the apertures 31 or will spill over the upper edge of the shell 43 into the comminution space 51. Some particles of course will pass directly into the comminution space 51 without having been subjected to any size reduction in the comminution space 50. Within the space 51 reduction in size is achieved by the relative movement between shell 42 and cone 34 and the gradual decrease of the spacing between these two members. Particles falling from the lower end of shell 43 will be of approximately the same size as the particles that have passed through the openings 31 in grate 30 and likewise in addition to having been reduced to desired size will have been retained within the apparatus long enough to be cooled as desired and give up their heat to the air passing through the cooler and into the kiln.

From the foregoing it will be apparent that the illustrated embodiment of the invention provides an improved apparatus for cooling material such as cement clinker discharged from a kiln and accordingly accomplishes the objects of the invention. On the other hand it will also be obvious to those skilled in the art that the invention may be utilized to advantage in the treating of any granular material with a gas and therefore the disclosure herein is illustrative only and the invention is not intended to be limited thereto.

Having now particularly described and ascertained the nature of my said invention and the manner in which it -is to be performed, I declare that what I claim is:

l. In an apparatus for cooling granular material, a first bin and wind box assembly, a second assembly including a shaft mounted over said first assembly, a motor connected to one of said assemblies to rotate said one assembly relative to the other assembly and about a central axis passing therethrough, means for delivering material to be treated to the top of said shaft for discharging material into said shaft, a blower connected to said first assembly for blowing gases upwardly through said shaft to cool said material, and discharge means comprising an annular grate supported by said first assembly, a plurality of arms adjacent the lower end of said shaft and connected to circumferential spaced points on said shaft, each of said arms extending inwardly toward the central axis of said shaft, a cylindrical shell suspended from the inward ends of said arms through the central opening of said annular grate with the central axis of said shell in a vertical position, and a crushing cone supported by said first assembly projecting upwardly into said shell, the relative movement between said assemblies imparting relative movement between said shell and said cone, and said shell being spaced apart from said cone to define therebetween comminution space where lumps larger than predetermined maximum size are retained until they are Iboth reduced in size and further cooled.

2. In an apparatus for cooling granular material, a first bin and wind box assembly, a second assembly including a shaft mounted over said first assembly, a motor connected to one of said assemblies to rotate said one assembly relative to the other assembly and about a central axis passingI therethrough, means for deliveringmaterial to'l be treatedi to the top-,of said shaft` fo'r dischargingrmaterial into said shaft, arl blower connected to said first assembly for blowing. gases upwardly through said shaft to cool said'rnaterial, and discharge means comprising. an annular grate supported by said' first assembly, a plurality. of` arms adjacent thel lower end of said shaft and connected to circumferential spaced pointson said shaft, each of said arms extending inwardly toward the central axis of said shaft, a plurality of teeth projecting up- -wardly from said grate toward said arms, a cylindrical shell suspended from the inward ends of said arms through the central opening of said annular grate with the central axis of said shell in a vertical position, and a crushing cone supported by said first assembly projecting upwardly into said shell, the relative movement between said assemblies imparting relative movement between said arms and said grate teeth and relative movement between said shell and said cone, and said arms being spaced apart from said grate teeth and said shell being spaced apart from said cone respectively to define therebetween comminution space where lumps larger than predetermined maximum size are retained until they are both reduced in size and further cooled.

3. In an apparatus for cooling granular material, a first bin and wind box assembly, a second assembly including a shaft mounted over said first assembly, a motor connected to one of said assemblies to rotate said one assembly relative to the other assembly and about a central axis passing therethrough, means for delivering material to be treated to the top of said shaft for discharging material into said shaft, a blower connected to said first assembly for blowing gases upwardly through said shaft to cool said material, and discharge means comprising an annular grate supported by said first assembly, a plurality of arms adjacent the lower end of said shaft and connected to circumferential spaced points on said shaft, each of said arms extending inwardly toward the central axis of said shaft, a first plurality of teeth projecting upwardly from said grate toward said arms, a second plurality of teeth projecting downwardly from said arms toward said first teeth, a cylindrical shell suspended from the inward ends of said arms through the central opening of said annular grate with the central axis of said shell in a vertical position, and a crushing cone supported by said first assembly projecting upwardly into said shell, the relative movement -between said assemblies imparting relative movement between said arm teeth and teeth and said grate teeth and relative movement between said shell and said cone, and said arm teeth being spaced apart from said grate teeth and said shell being spaced apart from said cone respectively to define therebetween comminution space where lumps larger than predetermined maximum size are retained until they are both reduced in size and further cooled.

4. In an apparatus for cooling granular material, a first bin and wind box assembly, a second assembly in cluding a shaft mounted over said first assembly, a motor connected to said second assembly to rotate said second assembly relative to the first assembly and about a central axis passing therethrough, means for delivering material to be treated to the top and near the periphery of said shaft for discharging material into said shaft, a blower connected to said first assembly for blowing gases upwardly through said shaft to cool said material, and discharge means comprising an annular grate supported by said first assembly, a plurality of arms adjacent the lower end of said shaft and connected to circumferential spaced points on said shaft, each of said arms extending inwardly toward the central axis of said shaft, a first plurality of teeth projecting upwardly from said grate toward said arms, a second plurality of teeth projecting downwardly from said arms toward said first teeth, a cylindrical shell suspended from the inward ends of said arms through the central opening of said annular grate with the central axis of said shell in a vertical position, and

a crushing Vcone supported by said first assembly proiecting upwardly into' said shell, the movement of said second assembly imparting movement between said arms and said grate, and said arm teeth lbeing spaced apart from said grate teeth and said shell being spaced apart from said cone respectively to define therebetween comminution spaces where lumps larger than predetermined maximum size are retained until they are both reduced in size and further cooled.

References Cited in the le of this patent UNITED STATES PATENTS Wolf June 5, 1883 Lellep Nov. 25, 19'5 8 FOREIGN PATENTS Great Britain of 1835 Great Britain July 31, 1891 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No., 3O63647 November I3, 1962 Otto George Lellep It is hereby Certified that ent requiring correction and that corrected below.

error appears in the above numbered pat- J@he said Letters Patent shouldread as Column q line I8g strike out and";

line 49, strike out, Vteeth" lrst occurrence.

signed and Sealed this. 30th day of Apr-i1 1963.

(SEAL) Attest:

ERNEST w. swlDER DAVID L LADD Attesing Ufficer Commissioner of Patents 

